At present, most of communication terminals support the mute mode (that is, a no-disturbing function). Thus, in some occasions (for instance, in a conference or sleep), a user is protected from disturbance of a call ring. However, on the other hand, it is also possible that some emergency or important calls are missed.
In the conventional art, when a telephone is in a mute mode, a terminal user may miss some emergency or important incoming calls, thereby reducing the user experience.